One of the important goals of developmental biology is to understand processes of limb morphogenesis. Remarkably, the many genes that control these processes have been conserved between insects and vertebrates, and the wing of Drosophila has proven to be a useful model for studying limb development. As a genetic tool, Drosophila is also a powerful system for the identification of genes required for many biological processes and the unbiased nature of forward genetics permits the identification of genes required for these processes that would not likely be found by any other means. Although a number of genes have been shown to be essential for the development of limbs, it is clear that many of the genes required for limb morphogenesis remain to be identified. Therefore, a systematic genetic screen to identify novel genes required for the specification, growth and patterning of Drosophila wings will be conducted. The method proposed for this screen is to generate clones of cells homozygous for newly induced mutations specifically in the developing wings of otherwise heterozygous flies, thus allowing the identification of genes required for limb development that may cause embryonic lethality in homozygous mutant animals. The genes disrupted by the mutations will be cloned and the roles of the encoded proteins in wing development will be studied. The identification of novel genes with this screen, and the subsequent characterization of their functions in wing morphogenesis, will advance our understanding of limb development.